Question

Calculate the value of free-board that should be provided for a reservoir having a wind velocity of 92 km/h and it extends up to 18 km upstream.

(a) 1.2 m

(b) 1.6 m

(c) 2.25 m

(d) 2.5 m

The question was posed to me by my college professor while I was bunking the class.

This key question is from Gravity Dam Design in chapter Gravity Dam Design and Construction of Irrigation Engineering

Answer 1

Correct option is (c) 2.25 m

To elaborate: When F < 32 km, the wave height is given by – Hw = 0.032(V.F)^1/2 + 0.763 – 0.271 F^1/4

Hw = 0.032(92 x 18)^1/2 + 0.763 – 0.271 (18)^1/4 = 1.5 m

Free board is generally provided equal to 1.5 Hw = 1.5 x 1.5 = 2.25 m.